U.S. Sees Extended 787 Inquiry

U.S. air-safety investigators said they remain stumped by "the sequence of events" that caused a lithium-ion battery to experience internal short circuits, overheat uncontrollably and burst into flames inside a parked Boeing Co. 787 in Boston earlier this month.

In the most detailed update yet of the intense fire aboard the Japan Airlines Co. Dreamliner Jan. 7, investigators Thursday appeared to largely eliminate few...